From 2e55bedc45e836899a18ea7f4a488f50597afad5 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Sat, 21 Sep 2024 19:31:16 +0200
Subject: misc
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Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 io.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)

(limited to 'io.c')

diff --git a/io.c b/io.c
index 6ee9e29..98afe53 100644
--- a/io.c
+++ b/io.c
@@ -2,6 +2,61 @@
 #include "common.h"
 
 
+void
+writeall(int fd, const void *data, size_t n, const char *fname)
+{
+	const char *text = data;
+	ssize_t r;
+
+	while (n) {
+		r = write(fd, text, n);
+		if (r < 0) {
+			if (errno == EINTR)
+				continue;
+			eprintf("write %s:", fname);
+		}
+		text = &text[r];
+		n -= (size_t)r;
+	}
+}
+
+
+void
+filecpy(int fd, off_t src, off_t len, const char *fname)
+{
+	char buf[8UL << 10];
+	ssize_t r;
+	size_t n;
+	size_t off;
+
+	while (len) {
+	read_again:
+		r = pread(fd, buf, sizeof(buf), src);
+		if (r <= 0) {
+			if (!r)
+				eprintf("%s: unexpected end of file", fname);
+			if (errno == EINTR)
+				goto read_again;
+			eprintf("pread %s:", fname);
+		}
+		src += (off_t)r;
+		len -= (off_t)r;
+		n = (size_t)r;
+
+		for (off = 0; off < n;) {
+		write_again:
+			r = write(fd, &buf[off], n - off);
+			if (r < 0) {
+				if (errno == EINTR)
+					goto write_again;
+				eprintf("write %s:", fname);
+			}
+			off += (size_t)r;
+		}
+	}
+}
+
+
 off_t
 filesize(int fd, const char *fname)
 {
@@ -23,3 +78,75 @@ filesize(int fd, const char *fname)
 
 	return st.st_size;
 }
+
+
+#if defined(__linux__)
+
+char *
+get_device_name(unsigned int devmajor, unsigned int devminor)
+{
+	char dev[2 * 3 * sizeof(int) + 3];
+	size_t devlen;
+	char buf[PATH_MAX];
+	struct dirent *f;
+	DIR *dir;
+	int dfd, fd;
+	ssize_t r;
+	size_t off;
+
+	devlen = (size_t)sprintf(dev, "%u:%u\n", devmajor, devminor);
+
+	dir = opendir("/sys/class/block");
+	if (!dir) {
+		weprintf("opendir /sys/class/block:");
+		return NULL;
+	}
+	dfd = dirfd(dir);
+	if (dfd < 0) {
+		weprintf("dirfd /sys/class/block:");
+		goto fail;
+	}
+
+	while ((errno = 0, f = readdir(dir))) {
+		if (f->d_name[0] == '.')
+			continue;
+		if (strlen(f->d_name) > sizeof(buf) - sizeof("/dev"))
+			continue;
+		stpcpy(stpcpy(buf, f->d_name), "/dev");
+		fd = openat(dfd, buf, O_RDONLY);
+		if (fd < 0)
+			continue;
+
+		off = 0;
+		while (off < sizeof(buf)) {
+			r = read(fd, &buf[off], sizeof(buf) - off);
+			if (!r)
+				goto complete;
+			if (r < 0) {
+				if (errno == EINTR)
+					continue;
+				goto next;
+			}
+			off += (size_t)r;
+		}
+		goto next;
+
+	complete:
+		if (off == devlen && !memcmp(dev, buf, devlen)) {
+			close(fd);
+			closedir(dir);
+			return strdup(f->d_name);
+		}
+
+	next:
+		close(fd);
+	}
+
+	if (errno)
+		weprintf("readdir /sys/class/block:");
+fail:
+	closedir(dir);
+	return NULL;
+}
+
+#endif
-- 
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